Telecommunication networks include circuit-switched networks such as plain old telephone service (POTS) and packet-switched networks such as the Internet protocol (IP) network to transport voice and data between remote end users. The circuit-switched networks utilize transmission paths dedicated to specific users for the duration of a call and employ continuous, fixed bandwidth transmission. The packet-switched networks allow dynamic bandwidth, and can be connectionless networks with no dedicated path or connection-oriented networks with virtual circuits having dedicated bandwidth along a predetermined path. Because packet-switched networks allow traffic from multiple users to share communication links, these networks use available bandwidth more efficiently than circuit-switched networks.
IP networks are connectionless packet-switched networks that break up streams of information into addressable packets. Each IP packet includes source and destination addresses and can take any available route between the source and destination. The IP packets are transmitted independently and then reassembled in the proper sequence at the destination.
In IP and other networks, voice mail systems are used to record an audio message from a calling party for an absent, busy or otherwise unavailable called party. Although most telephony systems allow for multiple lines, line appearances or call waiting, such systems do not allow a party leaving a message with voice mail to take an incoming call without terminating the voice mail connection or putting the connection on hold, in which case an awkward pause is left in the voice mail recording.